Explain why an external magnetic field leads to the splitting of energy levels by amounts of the order of u, b. (b) explain the following terms. your answer should indicate the circumstances under which each effect is observed. (i) normal zeeman effect (ii) anomalous zeeman effect (iii) paschen-bach effect (c) (i) a 500 nm spectral line splits into three lines with spacing 0.05 nm. what is the value of the magnetic field? (ii) into which of the above three categories does this example fall?